Then you have the proposal of development generating money for the stadium. The concept there is areas surrounding the stadium will be filled with condominiums, apartments, restaurants and retail stores. Those private businesses will be taxed and that money will go towards the cost of the new facility.
The problem with this idea is it takes a long time for the money to come in and the NFL has explicitly said they do not want new stadiums being financed this way. However, if it is only a small percentage of the total cost the league could look at it.
If there is no request for public tax dollars, no public vote would be necessary and the local government could conceivably vote on whether or not to go ahead with it in the next few months. However, San Diego Mayor Kevin Faulconer has promised a public vote on a new stadium and San Diego residents will likely still have input on the matter through a vote in some capacity.